1. Field of the Invention
The present invention relates to an optical disk recording and reproducing apparatus, and more particularly to an apparatus for recording and reproducing both an optical disk housed in a cartridge or a so-called mini disk and an optical disk not housed in a cartridge, by using the same disk motor and the same optical pickup.
2. Related Background Art
A mini disk (MD) is known as a rewritable optical disk, and a recording/reproducing apparatus for MD only is commercially available. A compact disk (CD) is also known which is an optical disk only for reproduction, and a reproducing apparatus for only CD and a reproducing apparatus compatible with both CD and other optical disks such as video disks are also commercially available.
In both CD and MD, an optical pickup applies a laser spot to the record track and receives the reflected light with a light receiving element whose output is used for reproduction.
However, CD and MD have the following different points. An optical disk of MD is housed in a cartridge. It is rotated by using the hole formed in the disk and recorded or reproduced by opening the shutter of the cartridge. An optical disk of CD is not however housed in a cartridge.
An optical disk of MD is held by a turntable having a magnet which attracts the metal plate attached to the optical disk. However, CD has no such a metal plate so that it is held by a turntable by pressing it against the turntable.
Although position alignment holes are formed in both CD and MD at the central area thereof, the hole of CD is larger than that of MD. In addition, although the hole of CD is a through hole, the hole of MD is a via hole closed at its upper end by the metal plate.
As above, although CD and MD have the same point that both are reproduced by using a reflected light of a laser spot, the disk structure and holding mechanism are different. Therefore, the optical disk holding and driving mechanism of a conventional optical disk recording and reproducing apparatus cannot hold and drive both MD and CD. A reproducing apparatus compatible with both MD and CD and capable of reproducing them by using the same disk motor and optical pickup, has not been realized as yet.